Ecophysiological and morpho-functional responses of mediterranean plants on coastal dunes: How they vary across seasons

Coastal dunes of the Mediterranean basin are threatened ecosystems, conservation of which is vital for both ecological and economic reasons. Understanding how dune plants and their habitat interact may deepen our knowledge of the dynamics of coastal environments. An ecophysiological and morpho-functional investigation was carried out throughout all seasons on four species typically found on the fixed dunes of central Italy. They belong to different functional groups: Cistus creticus subsp. Eriocephalus (drought semideciduous), Phillyrea angustifolia (evergreen sclerophyll), Juniperus macrocarpa (conifer) and Spartium junceum (leguminous). The aims of the study were to determine the annual patterns of plant responses, to highlight putative differences of resistance strategies between functional groups, and to identify traits which play a crucial role in plant adaptation to dune environments. Photochemical efficiency was lower in winter for all species, although it was quite steady in Juniperus. Water status never reached critical levels, probably because the summer under analysis was wetter than average. Different strategies of resistance were exhibited: leaf morphological traits and seasonal modulation of leaf pigments changed depending on the functional group. Nevertheless, all species displayed efficient adaptation to the Mediterranean environment involved in the study, showing the critical importance of how physiological and functional adjustments combine in different ways. In particular, leaf area, total carotenoid and total chlorophyll concentrations performed a prominent role in explaining how the studied plants adapt to the fixed dune environment.